A team's fourth down efficiency measures only the number of times a team is able to convert a fourth down into a first down. It does not count towards their efficiency rating if they punt the ball, make a field goal, or score a touchdown. This statistic is calculated by dividing the number of successful fourth down conversions by the total number of fourth downs. Essentially, this measures the number of times a team turns the ball over on downs.
Ideally, this number is as close to 100% as possible. If a team attempts to convert a 4thdown into a 1st down and consistently fails, they will have a low fourth down efficiency rating. Most teams do not attempt many 4th down conversions during the game because it is a risky play. Field position is an important part of the game, and surrendering field possession by turning the ball over on downs can lead to quick scores by the opposing team.